Modular bioelectrochemical systems and methods

ABSTRACT

Bioelectrochemical systems (BES) having configurations with spiral wound structures and with frame-and-plate structures are provided. Systems may allow for production of an electrical current that is at least partially generated by anodophilic microorganisms connected directly or indirectly to an electrode. A spiral wound or frame-and-plate type bioelectrochemical system may include an anolyte influent point, a catholyte influent point, electrodes, ion selective membranes, mesh separators, gas collection devices, an exterior containment vessel, and one or more external electrical devices.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/345,104, filed Sep. 8, 2014, entitled “Modular BioelectrochemicalSystems and Methods,” which is a U.S. National stage of expiredapplication No. PCT/US2012/055562, filed Sep. 14, 2012, entitled,“Modular Bioelectrochemical Systems and Methods,” which claims priorityto U.S. Provisional Patent Application No. 61/535,006, filed on Sep. 15,2011, entitled “Modular Bioelectrochemical System and Method”, and U.S.Provisional Patent Application No. 61/603,005, filed on Feb. 24, 2012,entitled “Bioelectrochemical Desalination Processes And Devices.” Theentire disclosure of each of these applications is incorporated hereinby reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

This invention was made with government support under grant numberN00014-10-M-0232 awarded by the Office of Naval Research. The governmenthas certain rights in the invention.

FIELD

This disclosure relates generally to devices for electricity productionor value added chemical production using a spirally woundbioelectrochemical system (BES) or microbial fuel cell (MFC). Morespecifically the present disclosure provides BES reactors withframe-and-plate structure, concentrically wound or similarconfigurations for simultaneous biodegradable material oxidation, energyproduction, chemical production, and/or desalination. The presentdisclosure also provides methods and devices for capacitive microbialdeionization of liquids using microbially charged capacitors to removecharged-carrying organic and/or inorganic aqueous material.

BACKGROUND

Worldwide concerns on environmental pollution, energy depletion, andclimate change are compelling environmental engineers to expand theirresponsibilities from pollution clean-up to sustainable development ofenergy and environmental systems. One emerging direction is to transformwastewater infrastructure from simple treatment processes to integratedenergy and valuable product recovery systems. Current wastewatertreatment processes and membrane based desalination technologies areenergy intensive due to the power demand for aeration, sludge treatment,and membrane operation. For example, it is estimated that every year,the U.S. uses approximately 57 Terawatt hours of electricity forwastewater treatment, accounting for 1.5% of the national totalelectricity production (equivalent to 5.4 million households' annualelectricity use. A sustainable approach to wastewater treatmentconsiders recovering the energy content of organic matters whilesimultaneously achieving treatment objectives because energy contentembedded in wastewater is estimated to be about 2-4 times the energyused for water infrastructure in the U.S. This means it may be possibleto make wastewater treatment self sufficient.

Furthermore, improving water supply and quality in many places aroundthe world would aid in mitigating many problems facing both developedand developing countries. The United Nations estimates that due to aglobal increase in population of 80 million people per year, anadditional 64 billion cubic meters per year of freshwater is required.Lack of water could lead to the displacement of 24-700 million people,greater national insecurity, and world conflict. Inadequate watersanitation and supply has been linked to many diseases such as malaria,cholera and typhoid. The world health organization estimates that, withimprovements to water supply, sanitation and hygiene 4%-75% of theglobal diarrhea disease burden could be prevented. It is apparent thatincreasing freshwater production would drastically improve humanity. Theproblem with increasing water supply is that energy is required for theproduction of all water, and water is required for the production of allenergy. This phenomenon, known as the water energy nexus, thus far hasprevented a sustainable method of producing energy or water. One clearindicator of the water energy nexus is that in the United States, waterused for cooling power plants equals the amount of water used foragriculture.

Currently the two main methods by which saltwater can be desalinated iswith electrodialysis (ED) or reverse osmosis. However, thesetechnologies are not sustainable because of the substantial amount ofexternal energy required. In 2008 a significant advance was made by thedevelopment of a microbial desalination fuel cells (MDC) which candesalinate water without any external energy. MDC technology usesmicroorganisms to oxidize a substrate, potentially municipal wastewater,to generate the energy required for desalination. The main problem withthe MDC technology is that the ions from desalination becomeconcentrated in the anode and cathode chambers. This concentration ofions in the anode and cathode chambers prevents MDC from being asustainable method for desalination. If wastewater was used as thesubstrate, the increase in total dissolved solids (TDS) can prevent thetreated wastewater from being reused.

With respect to wastewater, direct energy production from wastematerials via bioelectrochemical systems (BESs) offers economic andenvironmental benefits because the energy produced offsets the energyconsumption associated with treatment and reuse processes. BESs may usemicroorganisms to catalyze the oxidization of organic and inorganicelectron donors in the anode chamber and deliver electrons to the anode.The electrons may be captured directly for electricity generation, indevices such as microbial fuel cells (MFCs). In other examples, theelectrons may be supplemented by external power input for producinghydrogen, methane, or value-added chemicals in devices such as microbialelectrolysis cells (MECs). The electrons may also be used in the cathodechamber to remediate contaminants such as uranium, chlorinated solvents,and perchlorate. The potential across the electrodes may, in otherexamples, also drive desalination through MDCs.

Compared to traditional environmental technologies, which generallyprovide one approach for pollutant control, bioelectrochemical systemsoffer both oxidation and reduction approaches for waste treatment,contaminant remediation, energy and water recovery. On the anode side,BESs can theoretically oxidize any biodegradable substrate and extractelectrons to the anode. In addition to simple sugars and derivatives,many complex waste materials have been utilized such as differentwastewater, biomass, landfill leachate, and petroleum hydrocarbon. Onthe cathode side, any electron acceptor type of contaminants canpotentially be reduced using the electrons supplied from the cathode.Such contaminants include chlorinated solvents, perchlorate, chromium,uranium, etc.

An advantage of using BESs in wastewater treatment is its potential toconvert traditional energy intensive treatment processes into energygaining processes while still achieving treatment objectives. However,despite the great potentials BES offers in environmental engineering,the energy output highly depends on the degradability of the substrate,the reactor architecture, and the active microbial community. Though thepower density from lab scale, acetate based reactors has increased fromless than 1 mW/m² to 6.9 W/m² in the past decade, the power output fromreal wastewater is much lower compared to simple substrates due to thelow biodegradability, conductivity, and buffer capacity in wastewater.For example, by using the same configuration of lab scale reactors, themaximum power density achieved from acetate (1.69 W/m² or 42 W/m³) wasmore than 8 times higher than the power output from brewery wastewater(0.21 W/m², or 5.1 W/m³) according to one test.

The restraints of wastewater in power production from BESs become moreapparent in larger scale systems. Though the first 2 m pilot reactor hasbeen operating since 2007 in Australia using brewery wastewater, theperformance is reported to be unsatisfactory. One main reason identifiedis the low conductivity and alkalinity of the wastewater. The loss ofelectrons in the anode chamber results in the accumulation of protons,which will reduce the anode chamber pH and inhibit microbial activity.Therefore, lab scale studies generally use high strength phosphate orcarbon buffer solution (50-200 mM) to maintain pH neutrality. The buffersolution also provides additional conductivity to facilitate iontransfers to reduce system resistance. However, compared with bufferenhanced anolyte in lab studies, which keeps a neutral pH and highconductivity (˜20 mS/cm), real wastewater has a very low conductivity(1-2 mS/cm) and buffer capacity, leading to significant pH reduction andinternal resistance increase that results in reduced power output fromBESs. Because the continuous addition of buffer solution is costly andunsustainable, the nature of wastewater is one main challenge to beaddressed before BES can be utilized on a large scale. Another approachto minimize the internal resistance is to reduce the distance betweenthe electrodes. Porous separators such as J-cloth, glass fiber, and ionexchange membranes can reduce electrode spacing, provide electrodeinsulation, and decrease oxygen intrusion to improve electron recovery.Such separators are generally sandwiched between the anode and thecathode, but the reactor geometry becomes a challenge due to the risk ofshort circuit and deforming, especially when high surface brush anodewas used. Tubular configuration with brush anode surrounded by a layerof cloth cathode is currently considered relatively feasible for largerscale reactors, but this configuration has been associated with asignificant water leaking problems because the membrane/cathode assemblycannot hold the high static water pressure at larger scale. In addition,the low cathode surface area of the tubular design limited the poweroutput.

SUMMARY

According to various embodiments, the production of an electricalcurrent is at least partially generated by anodophilic microorganismsconnected directly or indirectly to an electrode. A spiral wound typebioelectrochemical system may include but is not limited to anolyteinfluent tube, catholyte influent tube, electrodes, ion selectivemembranes, mesh separators, gas collection device, an exteriorcontainment vessel around the spirally wound electrodes, exteriorcontainment for the ends of the reactor, and/or exterior containmentwith an air permeable electrode, and adhesive materials.

In one embodiment, the present disclosure provides a modularbioelectrochemical system (BES) reactor comprising a centrally locatedtube and spirally wound anode chamber. In this embodiment, anolyteenters the reactor from the centrally located tube, and flows from thecenter tube through perforated holes contained inside an anode chamber.The anode chamber is formed within the anode electrode, porous spacer,separator or ion selective membranes. The anolyte may flow through theanode chamber passively or through a series of channels formed by ionexchange membranes, physical separators, or adhesive materials. Theanolyte flows though the anode channel which is concentrically woundaround the center tube and back to the centrally located tube, or to anexternally located tube, to be expelled out of the reactor. The anodechamber contains, for example, an electrode which has acclimatedexoelectrogenic microorganisms. A catholyte, or electron acceptor, mayeither be directly connected to the anode chamber through an airpermeable cathode or can flow through a second centrally located tube orpassively flow through the top of the concentrically wound assembly.

Another embodiment in the disclosure provides a modular BES reactor inwhich an anolyte enters the reactor through an external tube which isconnected to an anode chamber concentrically wound around a centereffluent tube. The anolyte flows from the exterior of the reactorthrough the anode chamber formed by either an air permeable electrode oran ion exchange membrane. In some examples, the entire reactor may beplaced inside a containment vessel. The catholyte or electron acceptorcan either flow through an external tube directly connected to a cathodechamber concentrically wound around the center effluent tube, orpassively flow from the top of the reactor across the wound assemblagesformed by a porous spacer next to the anode chamber. There may bemultiple stacks of middle chambers separated from the anode and cathodechamber for desalination and other additional functions.

In other aspects of the disclosure, methods, systems, and devices aredescribed for bioelectrochemical processes that may be used for variouspurposes, such as desalination. Traditional desalination technologiesare energy intensive and generate large amount of concentrate. Someembodiments provide microbial capacitive desalination cells (MCDC) whichprovide a bioelectrochemical approach to achieve sustainable saltremoval and management. In some embodiments, salt removal and managementis achieved without using external energy. The MCDC addresses challengescurrently associated with microbial desalination cells (MDCs) includingsalt migration and pH fluctuation problems. Using high surface areaelectrode assemblies for capacitive adsorption of ions, the MCDCincreases desalination efficiency, in some embodiments, by 7-25 timesover capacitive deionization (CDI). Devised disclosed herein may alsoremove ions from the anode, cathode, and desalination chamber, whichenhances the reactor capability in simultaneous salt management,wastewater treatment, and energy production. Nearly full recovery ofsalt during MCDC regeneration also makes salt production possible,according to some embodiments.

DESCRIPTION OF THE DRAWINGS

FIGS. 1-2 are illustrations of a bioelectrochemical reactor according toan embodiment.

FIG. 3 illustrates the correlation between the charge potential acrossACC assemblies and the conductivity changes in the desalination chamberdue to electrical adsorption. Arrows indicate changes in electrolytesolution in batch cycles according to an embodiment.

FIG. 4 illustrates concentration changes of the four major ions(Potassium, Sodium, Chloride, Phosphate) before and after one typicalbatch cycle of MCDC operation according to an embodiment.

FIG. 5 illustrates initial starting point, the final point, and the ionsrecovered during regeneration of the high surface area electrodes in theoperation of a microbial capacitive desalination system according to anembodiment.

FIG. 6 illustrates electrode potential during regeneration of highsurface area electrodes the operation of a microbial capacitivedesalination system according to an embodiment.

FIG. 7 illustrates general design and operation of a capacitivemicrobial desalination system according to an embodiment.

FIG. 8 illustrates the current generated by the microorganisms over timein a capacitive microbial desalination system according to anembodiment.

FIG. 9 illustrates the adsorptive capacity of a capacitive microbialdesalination system according to an embodiment.

FIG. 10 illustrates the general diagram of the spiral woundbioelectrochemical system according to an embodiment.

FIG. 11 illustrates a cut out of general form of the microbial spiralwound system according to an embodiment.

FIG. 12 illustrates the operation of the microbial spiral wound systemaccording to an embodiment.

FIG. 13 illustrates some exemplary flow pathways between one or moremicrobial spiral wound systems according to various embodiments.

FIG. 14 illustrates different layers in a microbial spiral wound systemaccording to an embodiment.

FIG. 15 illustrates a cross sectional view of an exemplaryconcentrically wound microbial spiral wound system according to anembodiment.

FIG. 16 illustrates an exemplary winding for a microbial spiral woundsystem according to an embodiment.

FIG. 17 illustrates an exemplary fluid flow in an unrolled microbialspiral wound system according to an embodiment.

FIG. 18 illustrates an exemplary electrolyte fluid flow in an unrolledmicrobial spiral wound system according to an embodiment.

FIG. 19 illustrates ne of the options for fluid flow in an unrolledmicrobial spiral wound system according to an embodiment.

FIG. 20 illustrates cell voltage during the startup and operation of amicrobial spiral wound system according to an embodiment.

FIG. 21 illustrates the power density per cubic meter of anode fluid atdifferent anolyte flow rates in a microbial spiral wound systemaccording to an embodiment.

FIG. 22 illustrates power density per cubic meter of anode fluid atdifferent anode chamber volumes in a microbial spiral wound systemaccording to an embodiment.

FIG. 23 illustrates the internal resistance for a microbial spiral woundsystem according to an embodiment

FIG. 24 illustrates the correlation between the power density per cubicmeter and the coulombic efficiency for a microbial spiral wound systemaccording to an embodiment.

DETAILED DESCRIPTION

This description provides examples, and is not intended to limit thescope, applicability or configuration of the invention. Rather, theensuing description will provide those skilled in the art with anenabling description for implementing embodiments of the invention.Various changes may be made in the function and arrangement of elements.

Thus, various embodiments may omit, substitute, or add variousprocedures or components as appropriate. For instance, it should beappreciated that the methods may be performed in an order different thanthat described, and that various steps may be added, omitted orcombined. Also, aspects and elements described with respect to certainembodiments may be combined in various other embodiments. It should alsobe appreciated that the following systems, methods, devices, andsoftware may individually or collectively be components of a largersystem, wherein other procedures may take precedence over or otherwisemodify their application.

Bioelectrochemical systems (BES) having configurations with spiral woundstructures and with frame-and-plate structures are described for variousdifferent embodiments. Systems, devices, and methods are described formicrobial desalination cells (MDCs) that use electrical currentgenerated by microbes to simultaneously treat wastewater, desalinatewater, and produce bioenergy or biochemicals. A microbial capacitivedesalination cell (MCDC) addresses salt migration and pH fluctuationproblems facing current MDCs and improves the efficiency of capacitivedeionization. The anode and cathode chambers of the MCDC are separatedfrom the middle desalination chamber by two specially designed membraneassemblies, comprising cation exchange membranes and layers of activatedcarbon cloth (ACC). According to various embodiments, taking advantageof the potential generated across the microbial anode and theair-cathode, the MCDC may remove dissolved solids without using anyexternal energy. The MCDC desalination efficiency, according to variousembodiments, is significantly higher, and in some embodiments 7 to 25times higher, than traditional capacitive deionization processes.Compared to MDC systems, where the volume of concentrate can besubstantial, all or at least a significant amount of the removed ions inthe MCDC are adsorbed in the ACC assembly double layer capacitorswithout migrating to the anolyte or catholyte, and the electricallyadsorbed ions may be recovered during assembly regeneration. The twocation exchange membrane based assemblies allow the free transfer ofprotons across the system and thus prevent significant pH changesobserved in traditional MDCs.

The terms “microbial capacitive deionization cell” and microbialcapacitive desalination cell” are interchangeable and herein referred toas the devices. The devices of the present disclosure useexoelectrogenic microorganisms to catalyze the oxidation a reducedsubstrate and transfer electrons to an anode electrode. The electronsthen pass through an active electrode forming a capacitor for ionadsorption. The types of active electrode materials will be describedlater. The charge potential forming the capacitor is applied by thecharge potential difference between the anode and cathode electrodes.Electrolyte solution contained in the anode, cathode, and deionizationchambers are physically separated by ion exchange membranes.Deionization occurs in the devices by either electrochemically adsorbingthe ions directly from the electrolyte solution and/or by transferringthe ion from the anode or cathode electrolytes to the deionizationchamber for adsorption.

In some embodiments, devices of the present disclosure maybe used toproduce hydrogen gas or methane gas in a configuration referred to as amicrobial capacitive electrolysis deionization cell (MCEDC). The energyfor electrolysis may be supplied, in whole or in part, bybioelectrochemical reactors in combination with the MCEDC or through anexternal DC power supply.

In some embodiments, devices of the present disclosure maybe used toproduce inorganic and organic chemicals in a configuration referred toas a microbial chemical cell (MCC). The chemical production maybecatalyzed by enzymes or microorganisms.

Various embodiments of systems for deionization according to the presentdisclosure include applying the electrical potential to the activatedelectrode with a positive or negative potential placed next to a cationexchange membrane (CEM) adjacent to anode chamber. Additionally, theactivated electrode may be placed inside the anode and cathode chambersand/or inside a deionization chamber. The use of an anion exchangemembrane (AEM) in addition to a CEM placed next to either the anode orcathode chamber, according to some embodiments, allows for specificdesired ions to transverse ion selective barriers for device specificdesired results. One or more activated electrode assemblies, membranes,spacers, conductive electrodes, and seals may be used in variousembodiments, depending upon the particular requirements of anapplication.

With reference now to FIG. 1, an embodiment of the invention isdescribed. The apparatus of FIG. 1 is a frame-and-plate structure areaction vessel that provides general design and operation of amicrobial capacitive desalination system. The apparatus includes threereaction chambers, an anode reaction chamber 101 with an anode electrode102 and exoelectrogenic microorganism 103, a deionization ordeslaination chamber 112, and a cathode chamber 111. In thisconfiguration a CEM 104 is placed next to the anode chamber 101, and aCEM 109 is placed next to the cathode chamber 111. Activated highsurface area electrodes 106, 107 are placed inside the deionization ordesalination chamber and the potential from the anode chamber 101 isapplied to the activated electrode 106 next to the anode chamber 101.Current collectors 105, 108 are located adjacent to the electrodes 106,107, and provide an electrical connection to external electrical devices113. In operation the electrons generated in the anode chamber 101 passthrough to the first activated electrode 106 in the deionization ordesalination chamber 112 then through an electrolyte solution in chamber112 to the second activated electrode 108 and finally to cathodeelectrode 110. Anions 115 move towards the activated electrode 106 nextto the anode chamber 101 and cations 116 move towards the activatedelectrode 108 next to the cathode chamber 111. Additionally, cations 115move from the anode chamber 101 through the CEM 104 to the activatedelectrode 106. After the activated electrodes 106, 108 become saturatedin ions the potential from the anode 106 and cathode 108 electrodes areremoved, switched in polarity, or an externally applied DC potentialremoves the adsorbed ions. After all of the ions are removed from theactivated electrodes 106, 108 they are thus termed “regenerated”.

Electrons generated in the anode chamber 101 by microorganisms 103 aretransferred to an anode electrode 106 where they are transferred to anexternal electronic device 113 for storage or immediately applied to ahigh surface area electrode 106, 108 inside a desalination chamber.Cations and protons generated in the anode chamber 101 pass from theanode chamber 101 through the ion exchange membrane 104 and desalinationchamber 112 to the cathode chamber 111, illustrated by arrow 114, wherethey are reduced. The electrical potential generated on the high surfacearea electrodes 106, 107 form a capacitor for ion adsorption. When theelectrical potential is removed from the high surface area electrodes106, 107, the stored energy can be recaptured by the external electricaldevices 113. Ions adsorbed by the electrical potential are then desorbedfrom the high surface area electrodes 106, 107. External electricaldevices may include, for example, one or more of resistors, DC/DCinverters, computers, power sources, capacitors, transistors, and/orother electronic devices.

In some embodiments, multiple ion selective barriers with multipleactivated electrodes are included in a “stack configuration”.Alternatively multiple ion selective barriers may be used withintermittent activated electrodes assemblies. Charged ions pass througha chamber which either contains a charged activated electrode or throughthe electron motive force pass through a selective ion barrier to achamber which would contain an activated electrode for adsorption.

FIG. 2 illustrates the general design and operation of a microbialcapacitive desalination system according to an embodiment. In thisconfiguration, electrons generated in the anode chamber 201 bymicroorganisms 203 are transferred to an anode electrode 202 where theyare transferred to immediately applied to a high surface area electrode206 inside a desalination chamber 212. Ion exchange membranes 204, 209are placed adjacent current collectors 205, 208, in the anode chamber201 and cathode chamber 211. High surface area electrodes 206, 207 areplaced adjacent the current collectors 205, 208 in desalination chamber212. Cations and protons 213 generated in the anode chamber 201 passfrom the anode chamber 201 through the ion exchange membrane 204 anddesalination chamber 212 to cathode chamber 211 having a cathodeelectrode 210 where they are reduced. The electrical potential generatedon the high surface area electrodes 206, 207 form a capacitor for ionadsorption. When the electrical potential is removed from the highsurface area electrodes 206, 207 through current collectors 205, 208,the stored energy can be recaptured by external electrical devices. Ionsadsorbed by the electrical potential are then desorbed from the highsurface area electrodes 206, 207. In operation, cations 214 move fromthe desalination chamber to the first high surface area electrode,anions 215 move from the desalination chamber to the second high surfacearea electrode, and cations 216 move from the cathode chamber to thefirst high surface area electrode.

FIG. 3 depicts the operation of a microbial capacitive desalinationsystem according to an exemplary embodiment. Arrows indicate a singlebatch operation of the system. The graph shows that when the electricalpotential on the high surface area electrodes (ACC Assembly Potential)increases the conductivity or amount of free ions in solution decreases.When the electrical potential is removed conductivity or amount of freeions in solution returns to the starting operation.

FIG. 4 is a chart that illustrates the individual ion migration in amicrobial capacitive desalination system according to an embodiment.Ions in the desalination, anode and cathode chamber decrease from theinitial point to the final. This graph indicates that the electricalpotential applied to the high surface area electrodes in thedesalination chamber allows for the adsorption of ions from thedesalination chamber, anode chamber, and cathode chamber. Ions adsorbedfrom the anode chamber and cathode chamber must first migrate across theion exchange membrane.

FIG. 5 further depicts the operation of a microbial capacitivedesalination system. The graphs show the initial starting point, thefinal point and the ions recovered during regeneration of the highsurface area electrodes, for four major ions examined in the system.From the starting point as the electrical potential is applied to thehigh surface area electrodes all four major ions decrease inconcentration. When the electrical potential is removed from the highsurface area electrode the adsorbed ions can be fully released andrecovered in the regenerating solution.

FIG. 6 shows the regeneration of the high surface area electrodes. Whenthe high surface area electrodes are connected in direct short circuitthe electrical potential stored in the high surface area electrodesdissipates slowly, indicating that this system can be used as a energystorage device. If the high surface area electrodes are connected toexternal device, depicted in FIG. 1, the stored electrical potential canbe dissipated more quickly.

FIG. 7 illustrates a capacitive microbial desalination system of anembodiment. Similarly to the systems of FIGS. 1 and 2, the system ofFIG. 7 includes an anode chamber 701, having an anode electrode withassociated exoelectrogenic microorganisms 702 that is directly attachedto high surface area electrode 704. High surface area electrode 704,current collector 705, and ion exchange membrane 706 separate the anodechamber from deionization or desalination chamber 707. The deionizationor desalination chamber 707 is separated from cathode chamber 712, byion exchange membrane 708, current collector 709, and high surface areaelectrode 710. External devices 713 may be coupled with the electrodes704, 710, and may include one or more of resistors, DC/DC inverters,computers, power sources, capacitors, transistors, and/or otherelectronic devices. In operations, anions 714 move from the anodechamber 701 to the first high surface area electrode 704, anions 715move from the desalination chamber 707 to the first high surface areaelectrode 704, cations 706 move from the desalination chamber 707 to thesecond high surface area electrode 710 in the cathode chamber 712, andcations 717 move from the cathode chamber 712 to the second high surfacearea electrode 710. Electrons generated in the anode chamber 701 bymicroorganisms 702 are transferred to anode electrode which is directlyattached to high surface area electrode 704. The electrical potentialgenerated by the microorganisms 702 applied to the high surface areaelectrode 704 forms a capacitor for ion adsorption. Ions in thedesalination chamber 707 pass from the desalination chamber 707 throughion exchange membrane 706 and are adsorbed by the capacitor formed bythe electrical potential. Electrons travel from the anode chamber 701through external device 713 to the cathode chamber 712 where they arereduced.

FIG. 8 shows the current generated by the microorganisms over time inthe capacitive microbial desalination system of FIG. 7, for anembodiment. The percent salt removed from the desalination chamberincreases over time, indicating desalination. The arrows show when theelectrolyte media was replaced in a single batch system.

FIG. 9 illustrates the adsorptive capacity of the capacitive microbialdesalination system of FIG. 7, for an embodiment. Ions in thedesalination chamber migrate from the desalination chamber into theanode and cathode chambers. The high surface area electrodes operated asa capacitor for ion adsorption is indicated by no change in conductivityin the anode and cathode chambers.

In other embodiments deionization devices may be included that providefor deionization in a “spiral wound” or “flow through capacitor”.Instead of having the electrolytes flow through framed plate modules,such as described above, the electrodes, membrane sheets, and spacersare glued together to form a leaf, and multiple leaves are rolled uparound the collection tube. The anolyte and saline water may flowthrough separate channels, and air flow may be channeled through openpore spacers. The spacer directed electrolyte follow minimizes thedistance between the electrodes and reduces internal resistance that maybe present, such as resistance caused by low conductivity in wastewater,for example. The multiple layers of electrode/membrane assemblysignificantly increase the surface area to volume ratio, therebyproviding for higher energy output. Moreover, the divided narrow channelwithin one spiral wound module reduces the leaking risk caused by waterpressure in tubular systems.

In a flow through capacitor configuration the anode, cathode, anddeionization chamber are concentrically wound into a roll with spacers,ion selective barriers, and/or electrodes between the chambers. Theanode and cathode electrolytes flow separately into a chambers formed byion selective barriers and spacers. The deionization electrolyte flowsinto either a separate chamber with activated electrodes or throughincorporation with the cathode electrolyte. One or more of the influentsfor the electrolytes are centrally located with the effluent alsocentrally located with the concentrically wound layers on the outside ofthe influent and effluent points. To allow for fluid to flow through theinfluent, the concentrically around the wound layers and back to thecentrally located effluent, an adhesive or physical barrier may be addedto form a channel. Additionally, an electrolyte solution may be added tothe side of the concentrically wound layers so that flow of theelectrolyte would move perpendicularly to the wound layers.

Deionization devices of still other embodiments provide deionization ina “swiss roll” configuration. In a “swiss roll” device at least twoelectrolyte solutions flow into the reactor from the exterior of thedevice. The flow moves concentrically through wound anode, cathode, anddeionization chambers until the flow reaches a centrally locatedeffluent collection tube. Additionally, an electrolyte solution may beadded to the “swiss roll” device from the side of the reactor to allowflow to move perpendicularly across the wound layers.

With reference now to FIG. 10, a general diagram of the spiral woundbioelectrochemical system of various embodiments is described. Thesystem includes one or more influent and effluent ports connected tomultiple layers which could include anode electrodes, high surface areaelectrodes, separators, ion exchange membranes, cathodes or impermeablematerial. In the embodiment of FIG. 10, the system includes anelectrolyte influent/effluent tube 1001, concentrically wound layers1002 which may provide for passive electrolyte influent and effluent,and an outer layer 1003, which may be a membrane, electrode, separator,impermeable layer. A first middle layer 1004 may be a membrane,electrode, or separator; a second middle layer 1005 may, likewise, be amembrane, electrode, or separator; and an inner layer 1006 may be amembrane, electrode, or separator. The tube 1001 and layers 1003-1006may be housed in a container 1007 having an end cap 1008.

FIG. 11 shows a system of FIG. 10, partially in cross-section, thatillustrates an electrolyte distribution layer 1107 that includesapertures that allow electrolytes to be distributed to the differentlayers that are concentrically wound around the center tube 1101. Thesystem of FIG. 11, similarly as FIG. 10, includes electrolyteinfluent/effluent tube 1101, concentrically wound layers 1102 which mayprovide for passive electrolyte influent and effluent, and an outerlayer 1103, which may be a membrane, electrode, separator, impermeablelayer. A first middle layer 1104 may be a membrane, electrode, orseparator; a second middle layer 1105 may, likewise, be a membrane,electrode, or separator; and an inner layer 1106 may be a membrane,electrode, or separator. The spiral wound system of FIG. 11 may also behoused in a container, as described with respect to FIG. 10.

FIG. 12 depicts the operation of a microbial spiral wound system, whereelectrolytes flow into one or more tubes and are distributed intodifferent layers of electrodes, spacers, current collectors, membranes,or impermeable material. In addition to electrolytes flowing into one ormore tubes, electrolytes can passively flow across the concentricallywound layer. Current produced in the anode chamber is transferredthrough an external device such as a resistor to the cathode electrodewhere the electrons are terminally reduced. In the embodiment of FIG.12, concentrically wound layers 1201 are wound around effluent centertube 1202. Effluent flow from center tube 1202 is depicted by arrow1203, and influent flow into center tube 1212 is depicted by arrow 1207.Additionally, effluent flow from space between concentrically woundlayers is depicted at 1204, and influent flow into space betweenconcentrically wound layers is depicted at 1206. An outer layer orcontainer for the microbial spiral wound system 1205 may house portionsof the system. An external device 1208 may be coupled with the system,which may include one or more of resistors, capacitors, transistors,power sources, and/or other electronic devices.

In one embodiment, a 10-layer spiral-wound BES using an activated carboncloth electrode provides a surface/volume ratio can be increased byabout 56 times as compared to a traditional tubular BES. In oneembodiment, a spiral wound BES provides a surface/volume ratio of about350 m²/m³. Such a BES in some situations may be operated to provide apower density in excess of 1 kW/m³, which has been considered thethreshold for larger scale applications. In various embodiments, aspiral wound BES includes multiple layers of membranes, spacers, andelectrodes in a leaf cell. Activated carbon cloth may be used as theelectrode material, although other materials may be used as well. Carboncloth has a relatively high surface area and low price, making itattractive for many applications. Separators such as ion exchangemembranes and glass fibers may be used to insulate the electrodes toprevent short circuits.

FIG. 13 depicts some exemplary flow pathways between one or moremicrobial spiral wound systems. Other flow pathways will be readilyrecognized by one of skill in the art, as numerous different options areavailable for such pathways. For example, fluid can flow from the centertube of a first system to a second system center tube, as illustrated at1301. In another example, effluent may flow from space betweenconcentrically wound layers flowing into second passive flow spacebetween concentrically wound layers of another system, as illustrated at1302. In still another example, effluent may flow from space betweenconcentrically wound layers of a first system to the center tube of asecond microbial spiral wound device, as illustrated at 1303. In stillanother example, fluid can flow from the center tube of a first systemto passive flow space between the layers of a second system asillustrated at 1304. Fluid may also flow from the center tube to of areactor to the passive flow space of the same reactor, as illustrated at1305.

FIG. 14 illustrates composition of the different layers in the microbialspiral wound system of an embodiment. This embodiment includes ninelayers, from the inside to the outside: (1) a non-permeable material1401, (2) a spacer 1402, (3) an anode electrode 1403, (4) a spacer 1404,(5) an ion exchange membrane 1405, (6) a spacer 1406, (7) a cathodeelectrode 1407, (8) a spacer 1408, and (9) a non-permeable material1409. The two outer layers in this embodiment are not permeable andprovide for solution containment. The anode and cathodes are separatedby spacers and/or separators. The spacers may be used to direct liquidflow. In some cases, there can be multiple alternative layers of anionand cation exchange membranes between the anode and cathode chambers toform stacks or desalination chambers. Also, the cathode can be exposeddirectly to air as an air-cathode, so the spacer and non permeable layermay be omitted according to various embodiments.

FIG. 15 illustrates a cross sectional view of one option for theconcentrically wound microbial spiral wound system. In this embodiment,electrolyte enters and exits the concentrically wound layers from acenter tube 1501. Concentrically wound layers 1502 are wrapped aroundcenter tube 1501, with space for passive flow. In this embodiment, thelayers include an inner layer 1503, a middle layer 1504, and an outerlayer 1505. Various modifications to this design may be implemented,such as embodiments that have multiple influent and effluent tubes, withthe influent and effluent entering and exiting from multiple points ofthe concentrically wound system, for example.

FIG. 16 shows one option for winding the microbial spiral wound systemwhere two electrolytes enter tubes from the outside of wound layers, andthe electrolytes flow through the system until they are expelled by acenter tube. Additionally, a space between the two differentconcentrically wound layers allows for passive fluid flow. In thisembodiment, a first electrolyte influent 1601 is provided. Firstconcentrically wound layers 1602 are wound around an effluent tube 1603for the first and second electrolytes. A second set of concentricallywound layers 1604 are also wound around tube 1603. A second electrolyteinfluent is provided at 1605, and a space for passive fluid flow isprovided at 1606.

FIG. 17 shows an exemplary fluid flow in an unrolled microbial spiralwound system according to an embodiment. Electrolyte fluid flows intoone end of a center tube 1704 at an influent 1703, and enters a chamber1701 formed by two or more layers, the fluid flows around a barrier 1702in a U shape back to the original center tube to exit the reactor ateffluent point 1706. A center tube barrier 1705 provides a barrier tocenter tube 1705. An external device 1707 may be coupled with thesystem, which may include one or more of resistors, capacitors, powersources, and/or other electronic devices.

FIG. 18 shows an exemplary electrolyte fluid flow in an unrolledmicrobial spiral wound system according to an embodiment. In thisembodiment, electrolyte fluid flows into a centrically located tube1805, as indicated at 1803. The fluid then flows into a chamber 1804formed by two or more layers. The fluid flows inside the chamber 1804 asindicated by arrows 1807, and to a second tube 1802 which is used toexpel the fluid at effluent point 1806. One or more external devices1801 may be coupled with the chamber 1804, similarly as discussed above.

With reference now to FIG. 19 another option for fluid flow in anunrolled microbial spiral wound system is described. In this embodiment,electrolyte fluid enters the system through inlets 1904 and 1905 of twotubes 1903 and 1907. Fluid flows into two separated chambers 1902 and1906 and exit the system by flowing into a centrically located tube1901. The fluid flows inside the chambers 1902 and 1906 as indicated byarrows 1908. One or more external devices 1909 may be coupled with thechambers 1902 and 1906, similarly as discussed above.

FIG. 20 shows the startup and operation of an exemplary microbial spiralwound system, such as the system of FIG. 12. The system in thisembodiment acclimated in approximately 5 days and reached a maximumvoltage potential of 680 mV. The system was operated continuously at ahigh voltage for over 15 days. Carbon cloth was used as an exemplaryelectrode material, and the anode and cathode were connected using a1000 ohm external resistor. Voltage across the resistor was recordedevery 66 seconds using a data acquisition system.

FIG. 21 shows the power density per cubic meter of anode fluid atdifferent anolyte flow rates in a microbial spiral wound system, such asthe system of FIG. 12. The highest power density was achieved at a flowrate of 0.10 mL/min.

FIG. 22 show the power density per cubic meter of anode fluid atdifferent anode chamber volumes in a microbial spiral wound system, suchas the system of FIG. 12. The highest power density was achieved at avolume of 0.3 mL.

FIG. 23 shows the internal resistance for a microbial spiral woundsystem, such as the system of FIG. 12. The ohmic resistance wasidentified using electrochemical impedance spectroscopy. The internalresistance for the microbial spiral wound system was identified to be 13ohms.

FIG. 24 shows the correlation between the power density per cubic meterand the coulombic efficiency (CE) for a microbial spiral wound system,such as the system of FIG. 12. The CE illustrates the efficiency ofenergy transfer. The microbial spiral wound system of this embodimenthad a maximum CE of 2.8%.

In the exemplary embodiments described above, various methodology andreactor configurations for the microbial capactive deionization cell aredescribed in general. The electrodes, spacers, electrolytes, currentcollectors, ion selective barriers, catalysis, microbes, substrates, andassociated components may all be modified based on particularapplications in which the reactor may be used.

Electrodes

Electrodes in the present invention are described as electricallyconductive. The electrodes themselves have various shapes and sizesincluding but not limited to powder, granules, fibers, polymers, rods,felt, paper, wool, cloth, and brushes.

Anode Electrode

The following is a list of exemplary materials for use as the anodeaccording to various embodiments of the present invention: Carbon cloth,Carbon felt, Activated Carbon Cloth, Carbon wool, Graphite fiber,Conductive polymer, Metal mesh (Ti, Cu, Ni, Ag, Au, Steel), GraphiteBrush, Graphite Paper, Carbon aerogel, carbon nanotubes, graphene, andbiochar. Any of the previous conductive electrode material may be usesin any combination with each other.

Cathode Electrode

The following is a list of exemplary materials for use as the cathodeaccording to various embodiments of the present invention: Carbon cloth,Carbon felt, Activated Carbon Cloth, Carbon wool, Graphite fiber,Conductive polymer, Metal mesh (Ti, Cu, Ni, Ag, Au, Steel), GraphiteBrush, Graphite Paper, Carbon Aerogel, carbon nanotubes, biochar, carboncloth with catalysis coating, Teflon coated carbon cloth with catalysiscoating for use as an air cathode, graphene.

Adsorptive Electrode

The following is a list of exemplary materials for use as the adsorptiveelectrode material according to various embodiments of the presentinvention: Activated carbon cloth, activated carbon cloth with imbeddedtitania, Carbon Aerogels as monoliths, Carbon Aerogels as powders,Carbon Aerogel in microsphere form, Carbon Aerogels in thin filmcomposites, Carbon Aerogel silica modified, Carbon felt, Carbon black,Sintered activated carbons, Carbon nanotubes, biochar, and Blackmagnetite (Fe₃O₄)

Current Collectors

Current collectors, as used in the present disclosure, refer toelectrodes for the purpose of enhancing the electrical conductivity ofthe electrode materials. The following is a list of exemplary materialsfor use as current collectors: Aluminum, Copper, Titanium, Stainlesssteel, Nickel foils, Graphite, and graphene.

Spacers

Spacers, as used in the present disclosure, refer to non conductivematerial added to the reactor devices to provide a space for fluids toflow or prevent conductive materials from connecting. The following is alist of exemplary materials for the use as a spacer in variousembodiments: Nylon, Polyester, Polyethylene, Polypropylene, PEEK, PETG,PTFE, and PVC. All of the previous materials for spacers may be, forexample, solid sheets or in a mesh format with the following meshdesigns: Woven, Perforated, Knitted, and Molded.

Ion Selective Barriers

Ion selective barriers according to various embodiments are defined asbarriers allowing for the transport of ion specific molecules. Thefollowing is a list of exemplary ion selective barriers: Anion exchangemembranes, Cation exchange membranes, Proton exchange membranes,Ultrafiltration membranes, bipolar membranes, and ion exchange resins.

Catalyst

A catalyst is described in the present disclosure as enhancing a desiredreaction. The following is a list of exemplary catalyst for variousembodimetns: Platinum, Nickel, Copper, Tin, Iron, Palladium, Cobalt,tungsten, CoTMPP, and microbes.

Microbes

Microbes in the present disclosure refer to any microorganism that canexoelectrogenically transfer electrons. This includes microbe for theselective transfer of electrons to an anode, as well as electronscapable of accepting electrons from an electrode.

Examples of microbial families capable of exoelectrogenic transfer are:Aeromonadaceae, Alteromonadeceane, Clostridiaceae, Comamonadaceae,Desulfuromonaceae, Enterobacteriaceae, Geobacteraceae, Pasturelaceae,and Pseudomonadaceae.

Electrolytes Generally

Electrolytes in the present disclosure are defined as a solutioncontaining dissolved charged ions. The electrolyte may be used as thesubstrate for energy production, electron acceptance, or specificallyfor ion removal.

Anolyte

The anolyte in the present disclosure is the electrolyte solution addedto the anode chamber of the devices. Various embodiments of the presentdisclosure are designed to specifically use wastewater containingvarious substrates for energy production. The following is a list ofexemplary substrates: Carbohydrates, proteins, Lipids, Food waste,municipal waste, agricultural waste, industrial waste, produced water,reduced sulfur molecules, reduced iron molecules.

Catholyte

The following is a list of exemplary catholytes for use in the presentdisclosure: Potassium ferricyanide, solid peroxides, potassiumpermanganate, oxygenated salt water, trichloroethylene, persulfate, andoxidized uranium.

Deionization Electrolytes

The following is a list of exemplary electrolyte for deionization in thepresent disclosure. Saline water with 3-50 parts per thousand TDS.Brackish water with 0.5-3 part per thousands TDS, “Produced water” fromoil or natural gas production containing hydrocarbon and saline water.Fresh water with micropollutants including but not limited to nitrates,phosphates, perchlorates, and bromates,

Associated Components

The following is a list of exemplary associated components for thepresent disclosure: Pumps, valves, external power source, gas collectiondevice, external power collector, external conductors, externalinducers, switches, and external resistors.

It should be noted that the methods, systems and devices discussed aboveare intended merely to be examples. It must be stressed that variousembodiments may omit, substitute, or add various procedures orcomponents as appropriate. For instance, it should be appreciated that,in alternative embodiments, the methods may be performed in an orderdifferent from that described, and that various steps may be added,omitted or combined. Also, features described with respect to certainembodiments may be combined in various other embodiments. Differentaspects and elements of the embodiments may be combined in a similarmanner. Also, it should be emphasized that technology evolves and, thus,many of the elements are exemplary in nature and should not beinterpreted to limit the scope of the invention.

Having described several embodiments, it will be recognized by those ofskill in the art that various modifications, alternative constructions,and equivalents may be used without departing from the spirit of theinvention. For example, the above elements may merely be a component ofa larger system, wherein other rules may take precedence over orotherwise modify the application of the invention. Also, a number ofsteps may be undertaken before, during, or after the above elements areconsidered. Accordingly, the above description should not be taken aslimiting the scope of the invention.

What is claimed is:
 1. A reaction vessel to facilitatebioelectrochemical desalination of influent fluid, comprising: an anodereaction chamber comprising one or more anode elements in fluidcommunication with an anode electrolyte solution, and one or moremicroorganisms associated with the one or more anode elements; a cathodereactor chamber comprising one or more cathode elements in fluidcommunication with a cathode electrolyte solution; one or moredeionization or desalination chambers with a desalination ordeionization electrolyte solution in ion communication with the anodeelectrolyte solution and cathode electrolyte solution, and that includeone or more electrode elements; a first ion exchange membrane (IEM)located intermediately in the anode chamber and the one or moredeionization or desalination chambers; and a second IEM locatedintermediately in the one or more deionization or desalination chambersand the cathode chamber.
 2. The reaction vessel as claimed in claim 1,wherein the one or more deionization or desalination chambers compriseone or more electrode elements (i) electrically connected to the one ormore anode elements, one or more cathode elements, or combinationsthereof, and (ii) configured to adsorb ions from the desalination ordeionization electrolyte solution.
 3. The reaction vessel as claimed inclaim 1, wherein the one or more anode elements, the one or more cathodeelements, the one or more electrode elements, or any combinationthereof, comprise high surface area electrodes.
 4. The reaction vesselas claimed in claim 1, wherein the one or more anode elements, the oneor more cathode elements, the one or more electrode elements, or anycombination thereof, comprises a porous electrically conductingmaterial.
 5. The reaction vessel as claimed in claim 1, furthercomprising one or more current collectors positioned next to the one ormore anode elements, the one or more cathode elements, or combinationsthereof.
 6. The reaction vessel as claimed in claim 1, wherein anegative potential generated by microbial activities on the one or moreanode elements drives electrons to transport from the anode chamber toone or more of the deionization or desalination chamber electrolytes orone or more external resistors, and finally to the one or more of thecathode electrode elements.
 7. The reaction vessel as claimed in claim1, wherein cations or anions in the anode chamber or the one or moredeionization or desalination chambers move towards and get adsorbed bythe one or more anode elements.
 8. The reaction vessel as claimed inclaim 1, wherein cations or anions in the cathode chamber ordesalination chamber move towards and get adsorbed by the one or morecathode elements.
 9. The reaction vessel as claimed in claim 1, whereinthe first and second IEM are cation exchange membranes (CEM), anionexchange membranes (AEM), or any combination thereof.
 10. The reactionvessel as claimed in claim 1, wherein the reaction vessel is a frame andplate reaction vessel.